IS [ NOT ] DISTINCT FROM
Compares whether two expressions are equal (or not equal). The function is NULL-safe, meaning it treats NULLs as known values for comparing equality. Note that this is different from the EQUAL comparison operator (=), which treats NULLs as unknown values.
Syntax
Section titled “Syntax”<expr1> IS [ NOT ] DISTINCT FROM <expr2>Returns
Section titled “Returns”The value returned depends on whether any of the inputs are NULL values:
- Returns TRUE, if:
<null> IS NOT DISTINCT FROM <null><null> IS DISTINCT FROM <not_null><not_null> IS DISTINCT FROM <null>
- Returns FALSE, if:
<null> IS DISTINCT FROM <null><null> IS NOT DISTINCT FROM <not_null><not_null> IS NOT DISTINCT FROM <null>
- Otherwise,
<expr1> IS DISTINCT FROM <expr2>is equivalent to<expr1> != <expr2><expr1> IS NOT DISTINCT FROM <expr2>is equivalent to<expr1> = <expr2>